The late 1960""s witnessed a gradual change from conventional wood rackets to metal and plastic ones. These changes produced new challenges to the stringing of the rackets because the new materials produced new stresses on the string materials as well as on the rackets themselves. For example, the Wilson T2000 racket supported the strings from metal wire wound around the metal frame. Other designs utilized plastic grommets around the strings, at the contact points with the frame, to reduce the stress on the strings thereby reducing the probability of string failure.
In the 1970""s and 1980""s virtually all tennis rackets were made of plastic composites, utilizing the special properties, relating to strength and weight, of these high-tech materials. These new designs made possible the return to the more conventional stringing design and process, where the strings were woven through holes at the periphery of the racket head, as in the original wood rackets. This period also saw the emergence of numerous racket sizes, e.g. the mid and oversize rackets, tailored to the specific needs and capabilities of the players.
During especially the 1990""s special attention was placed not only the strength and weight of the rackets, but to their specific vibrational and torsional properties.
These vibrational and torsional properties have a considerable affect on the response of the racket at the moment of impact with the ball, which in turn improve the reliability of the bounce and lower the stress on the player""s arm and wrist.
Along the way improvements were also made to the strings and to string pattern design. New synthetic and composite fibers were made to increase their performance and to withstand the higher tensions utilized especially by the more skilled players. The string pattern was also redesigned in most instances, whereby there was a denser spacing of the strings near the center of the racket head, increasing the xe2x80x9csweet spotxe2x80x9d of the strike area.
The combined result of all these changes on the game of tennis has been nothing short of revolutionary. The pace of the game increased dramatically, and gave the professionals considerably more control over the flight of the ball. The impact on the non-professional varied according to their level of expertise.
Despite the improvements mentioned above, the overall stringing design has not changed dramatically from the days of the wooden rackets (except for the slight variations in string spacing). A modern string pattern still consists of string spaced roughly xe2x85x9c in. To ⅝ in. apart. This often leads to significant movement of the strings, in the plane of the racket head, due to the high spin introduced to the ball at the moment of impact, and causes an uneven and irregular spacing of the strings. This in turn makes subsequent bounces less reliable, and often results in string failure. A common sight at professional matches is the readjustment of the strings by the players between points; in fact, tools have been designed and patented specifically for this string adjustment. Also, despite the dramatic improvement in materials, the breakage of string is a common occurrence due to the enormous stresses experienced by these modern rackets and strings.
It is also significant that the stringing of the racket is done by hand, by individually weaving the string through the holes in the racket head and between the other strings. It requires considerable skill and expertise to achieve the level of consistency and reproducibility required by the top players.